Help! Overheating after repasting

[PowerPCFan]

So i've always wanted to replace my 12'' PowerBook g4 867mhz hard drive, and I always wanted to repaste it, too. I took off the heatsink, cleaned the CPU and heatsink with alcohol wipes, let it dry, and then I applied a small dot of Arctic MX5. When I was trying to take off the heatsink to get to the CPU, the two main screws holding it down sort of broke. They are these strange spring loaded things with all sorts of nuts and bolts attached to it. They don't want to screw back in, so I just left them out. (there's a few other screws to help hold it down) I halfway reassembled the computer to test it and the temps were fine when I checked my iStat menus, but only about 20 seconds after starting an xBench stress test the fan kicked on and the temps climbed up to 70 degrees Celsius. That's pretty hot for a PPC chip, and it never got above 62 degrees Celsius before I disassembled it. It was thermal throttling and I didn't want to damage the chip so I ended the test but I bet they would have climbed much higher if I hadn't stopped it.

Anyone know what I can do to better secure the heatsink to the logic board? I'm afraid those two screws will never go back in ever again

 

[RokinAmerica]

Half the hold down screws are missing. Those screws are to hold it in secure. Without out them you can't expect the paste to help.

 

[ervus]

I would suggest repairing the heatsink mounts.

forums.macrumors.com/threads/powerbook-g4-12-maintenance-servicing.2243978/

 

[AphoticD]

I’ve found with first time PBG4 12” tear downs, at least one of these posts has broken off the logic board.

They appeared to have been glued on, and after nearly two decades of cooking under the heat, the glue has given out.

As I mentioned in the linked maintenance thread, I have found that reseating the posts by soldering a ball from the underside of the board to lock it in has worked for me.

I have also had success with epoxy fixes. So if you don’t have access to a soldering iron, then try something reliable like JB Weld “Cold Weld” epoxy, as it has a high degree of heat resistance and many great uses

 

[PowerPCFan]

Half the hold down screws are missing. Those screws are to hold it in secure. Without out them you can't expect the paste to help.

I know that I hope my mac isn't broken, it's my favorite

 

[PowerPCFan]

I would suggest repairing the heatsink mounts.

forums.macrumors.com/threads/powerbook-g4-12-maintenance-servicing.2243978/

I’ve found with first time PBG4 12” tear downs, at least one of these posts has broken off the logic board.

They appeared to have been glued on, and after nearly two decades of cooking under the heat, the glue has given out.

As I mentioned in the linked maintenance thread, I have found that reseating the posts by soldering a ball from the underside of the board to lock it in has worked for me.

I have also had success with epoxy fixes. So if you don’t have access to a soldering iron, then try something reliable like JB Weld “Cold Weld” epoxy, as it has a high degree of heat resistance and many great uses

Thanks for the help! By the way, one of the posts is stuck in the heatsink so that will never come out. That unfortunately means the heat sink will never sit flat unless I get that out. The other one is still attached but it is spinning due to not being glued in place anymore.

 

[PowerPCFan]

Why did Apple use those dumb springy posts instead of a socket and a normal screw?!

 

[B S Magnet]

Why did Apple use those dumb springy posts instead of a socket and a normal screw?!

“Dumb, springy posts” are needed to assure a firm, even fit between CPU and heatsink across the tiny variances which can occur in mass-manufacturing. Moreover, the “dumb, springy posts” are needed to accommodate different types of thermal media between heatsink and CPU/GPU — whether it’s paste or pad. For the 12-inch PowerBook (and 12-inch iBook G4s), Apple had to work within pretty tight space constraints.

Variations on the “dumb, springy post” exist across multiple PowerBook and MacBook/Pro models. Sometimes, it’s a post with a spring, and sometimes, it’s a special, springy washer and screw combo.

 

[micahgartman]

The 12-inch PowerBook uses thermal pads in lieu of thermal paste. The spring-loaded screws ensure the connection isn’t overtorqued.

 

[AphoticD]

Thanks for the help! By the way, one of the posts is stuck in the heatsink so that will never come out. That unfortunately means the heat sink will never sit flat unless I get that out. The other one is still attached but it is spinning due to not being glued in place anymore.

Could you hold the post with pliers to unscrew and separate it from the heatsink?

 

[Certificate of Excellence]

I had one of those mounts snap (not come off the pcb, rather physically snap in half lol) during maintenance and successfully used extra strength super glue to reattach it and stay together under load (still affixed years later), so you have a number of options to reattach those mounts if you are not confident with a soldering iron or do not have one. I successfully used exactly the method that @AphoticD recommended to get the mount unscrewed from the pin that was stuck through the heat sink in preparation for the mount repair.

The thermal pad thicknesses I use for powerbooks are 1mm and 2mm thermal pads. They're about 6-7$ US each shipped off ebay for a sheet.

 

[PowerPCFan]

Could you hold the post with pliers to unscrew and separate it from the heatsink?

I tried, but there’s a nut on the post stopping it from turning. Maybe I can use the pliers on the nut first.

Can’t try right now, because I don’t have access to my PPC macs for the next few days, but maybe I’ll try on Monday/Tuesday.

 

[PowerPCFan]

I’ve heard everybody mention thermal pads. I kept the purple pads on and reused them because they were still sticky and pasty and I used thermal paste instead of the dried up white thermal pad on the cpu.

I really do think it’s ok to put paste instead of a pad on the CPU. I have put Arctic MX5 on many Apple laptops and desktops that used pads before, and they work better than ever, no overheating.

Also, I know that pretty high temps around 90 degrees Celsius are OK for newer machines, but what would be considered overheating for an old PPC mac?

And what’s a good place where I could buy more 512/1gb sticks of Ram? My liquid cooled G5 with a blazing fast CPU only has 1.5 gb RAM. Is aftermarket ram better? Or should I keep an eye out on eBay??

 

[Amethyst1]

Also, I know that pretty high temps around 90 degrees Celsius are OK for newer machines, but what would be considered overheating for an old PPC mac?

The 1.5 GHz 12” PowerBook turns off when the CPU reaches 75 degrees Celsius. This is the thermal emergency shutdown.

 

[PowerPCFan]

Just bought some jb weld cold weld epoxy, that will arrive over the weekend. In the meantime I will attack the heat sink with needle nose pliers and “try to unstuck a screw”